MTR3000 Repeater

[zerodayjames]

The dynamic range at that span is not that great. To get a better idea of how low the notch goes do this:

Set freq to the notch
Set span to 1 MHz or less, you want the pass off the display, just the notch
Input attenuator to 0, RF preamp on
Set your bandwidth (RBW/VBW auto) to 3 kHz. Slower the better
Tracking generator level to 0 dBm then normalize the display
Have at it
If you want to take the "hair" out of the bottom of the notch try changing the trace to power average and wait a bit.

Remember that span and bandwidth are your friends as far as sensitivity is concerned. You'll want to do the notch last then go back to a larger span to just eyeball how it all looks.

You are using a dummy load on the unused duplexer port and attenuators on the analyzer ports to soften any impedance mismatch, right?

I went back to using the T connector to hit each can individually. I lowered the bandwidth to 3kHz and reduced the span to 5 MHz. TG is at 0. The results are about the same. I am tuning the pass first, then the notch to dial things in.

I am using a dummy load when tuning the cans while they are connected. I am not using attenuators. Can you please provide a link or maybe more information on how to properly get these connected?

On a side note, I am hearing a sound of metal clanking from the cans from time to time. This usually happens later in the day when the temps start to rise. No more than 82F though. Is this normal?

 

[Ubbe]

If you connect just two cans and measure, you still get that 70dB rejection? Then switch out one can for the third and if measure -70dB then it's all about the instrument not handling that dynamic range and you actually have a 110dB rejection using three cans. If the coax leaks, or the instrument or the dummy load or whatever that are in the chain, it should show if the levels change when you run your hands around the coaxes and instrument and dummy loads.

/Ubbe